docs: def build_directory(
      sass_path, css_path, output_style='nested',
      _root_sass=None, _root_css=None, strip_extension=False,
  ):
      """Compiles all Sass/SCSS files in ``path`` to CSS.
  
      :param sass_path: the path of the directory which contains source files
                        to compile
      :type sass_path: :class:`str`, :class:`basestring`
      :param css_path: the path of the directory compiled CSS files will go
      :type css_path: :class:`str`, :class:`basestring`
      :param output_style: an optional coding style of the compiled result.
                           choose one of: ``'nested'`` (default), ``'expanded'``,
                           ``'compact'``, ``'compressed'``
      :type output_style: :class:`str`
      :returns: a dictionary of source filenames to compiled CSS filenames
      :rtype: :class:`collections.abc.Mapping`
  
      .. versionadded:: 0.6.0
         The ``output_style`` parameter.
  
      """
      if _root_sass is None or _root_css is None:
          _root_sass = sass_path
          _root_css = css_path
      result = {}
      if not os.path.isdir(css_path):
          os.mkdir(css_path)
      for name in os.listdir(sass_path):
          sass_fullname = os.path.join(sass_path, name)
          if SUFFIX_PATTERN.search(name) and os.path.isfile(sass_fullname):
              if name[0] == '_':
                  # Do not compile if it's partial
                  continue
              if strip_extension:
                  name, _ = os.path.splitext(name)
              css_fullname = os.path.join(css_path, name) + '.css'
              css = compile(
                  filename=sass_fullname,
                  output_style=output_style,
                  include_paths=[_root_sass],
              )
              with io.open(
                  css_fullname, 'w', encoding='utf-8', newline='',
              ) as css_file:
                  css_file.write(css)
              result[os.path.relpath(sass_fullname, _root_sass)] = \
                  os.path.relpath(css_fullname, _root_css)
          elif os.path.isdir(sass_fullname):
              css_fullname = os.path.join(css_path, name)
              subresult = build_directory(
                  sass_fullname, css_fullname,
                  output_style=output_style,
                  _root_sass=_root_sass,
                  _root_css=_root_css,
                  strip_extension=strip_extension,
              )
              result.update(subresult)
      return result